Specificity for homonymous pathways following repair of peripheral nerves with treated skeletal muscle autografts--in the primate.

While distal influences acting both tropically and trophically upon regenerating nerve fibres are not in doubt, the specificity of such influences is unresolved. The present experiments were designed to test whether pioneering axons regenerating through a large muscle graft showed specificity for their homonymous distal stumps if faced with a choice of pathways. Regeneration was assessed with respect to nerve conduction, the electromyograph, isometric tension and morphological indices of nerve regeneration in the median and ulnar nerves of non-human primates. Reinnervation of both distal stumps with functional neuromuscular transmission was found to take place by growth of nerve fibres from either proximal nerve into either distal stump. There was thus no evidence of specific homonymous reinnervation. The implications of this finding are discussed from a mechanistic and a clinical point of view.